Hello
We have encountered a couple of issues while trying to run our iOS application under MetalGL:
1. MetalGL does not support our texture format:
[***MetalGL ERROR***] GL_INVALID_OPERATION. glCompressedTexImage2D(): Vertically flipping PVRTC compressed texture format GL_COMPRESSED_RGB_PVRTC_2BPPV1_IMG is not supported.
2. MetalGL crashes whenever a uniform location of -1 is passed to glUniform() with EXC_BAD_ACCESS (code=1, address=0x18). Directly before the crash the following message is written:
[***MetalGL ERROR***] GL_INVALID_OPERATION. glUniformMatrix4fv(): Shader program 1 does not contain a uniform at location -1.
The OpenGL documentation says that glUniform() should be fed with a value returned by glGetUniformLocation() and
the latter officially returns -1 if some conditions are met. Therefore MetalGL should not only not crash but also support -1 as valid input.
3. The extension ‘APPLE_texture_max_level’ is not supported. This is a minor issue and could easily be circumvented in our application.
I hope this helps to improve MetalGL. If you happen to solve the first two issues I will take another look at MetalGL to check whether it is compatible enough for our application.